Growing medium for plants

ABSTRACT

The present invention provides a plant growth media which comprises small tufts of mineral wool having dispersed therein, particles of acidic phenolic resin for pH control and particles of vermiculite. The ingredients and structure of the product results in a lightweight growth media having a suitable pH for growing certain plants while also providing for flowability, enhanced water adsorption and cohesiveness which prevents the composition from spilling out of certain types of plant containers. The composition also provides enhanced root anchorage without sacrificing the properties of flowability and water adsorption. The composition also optimizes other features which makes the composition and ideal plant growth media.

BACKGROUND OF INVENTION

The present invention pertains to the art of growing plants andartifical media useful for growing the plants.

BACKGROUND INFORMATION

Various types of compositions have been developed for germinating seedsand growing plants. Generally, these compositions provide an environmentfor plant growth which simulates, to varying degrees, the conditionsfound in the natural or native soil. Compositions of this type weredeveloped because it is not always desirable to use native soil forgerminating seeds or growing plants. Native soil often contains manyingredients, some of which may actually hinder the growth of the plants.Disease organisms may also be present in native soil and these organismsare difficult to eliminate. Also,the soils from one location to anothermay vary considerably, thus making a uniform product difficult toformulate from native soil sources. Additionally, the structure of thenative soil does not always provide the optimum environment for plantgrowth. Often times the native soil is too compact for many types ofplants. For these reasons, different types of synthetic growing mediahave been developed for the purpose of providing uniform, predictablegrowth conditions which can be modified in accordance with theparticular growth requirements of any plant being cultivated.

Ideally, a synthetic plant growth medium should provide proper soilstructure for plant growth. This structure should be sufficiently porousfor moisture retention and it should have the ability to containsufficient air therein to satisfy the plant root requirements foroxygen. It should also be able to provide for proper chemicalenvironment, such as pH, for optimum growth. It should be flowable foreasy packaging, handling and use in different types of containers while,at the same time, it should be lightweight and capable of providingadequate anchorage for the roots so that the plants are not easilyknocked over.

The materials used in the composition should be sufficiently cohesive sothat they do not easily spill out of their container. However, thisquality of cohesiveness should not be optimized at the expense of theproperty of flowability.

The ingredients should be free of disease or toxid materials. Theyshould be compatible with each other and be capable of releasing thenecessary plant nutrients for optimum growth. It should be easilymanufactured and the ingredients should be inexpensive. Finally, itshould be durable and retain its structure and properties for a longtime.

It has generally not been possible to combine all the ideal featuresspoken of above, in a single composition. Usually, one or a fewqualities are stressed at the sacrifice of others. For example, wateradsorption has been optimized in some compositions by the use of certainporous ingredients while the ability to provide root anchorage has beensacrificed.

For example, one type of plant growth medium comprises shreddedstyrofoam. U.S. Pat. No. 2,891,355 typifies compositions of this type.The shredded Styrofoam requires the addition of a detergent to providethe necessary water adsorbency so that the medium is able to containsufficient moisture to sustain plant gowth. composition of this typegenerally do not provide a complete medium for optimum plant growthconditions. The shredded Styrofoam lacks the type of soil structurerequired for proper anchoring of the plants and, thus, the plants tendto be weak and can easily fall over due to insufficient anchorage. Also,any plant nutrients incorporated into the Styrofoam are easily leachedout of the zone of growth when the plant is watered.

U.S. Pat. No. 4,174,957 provides a synthetic growing mixture whichcomprises a mixture of urea-formaldehyde foam ganules, powdered peat orhumus and a wetting agent to help promote water adsorption. Thecomposition of this patent lacks sufficient structure to provide foreffective root anchorage. Also, the composition of this patent requirespeat or humus which is a naturally occuring organic soil additive whichwill eventually break down. Thus, after a period of time, only theurea-formaldehyde will remain in the composition since the othercomponents will either break down or be leached away. Furthermore, thepeat or humus, being a naturally occuring soil component, could easilyintroduce disease organisms into the growing medium.

Other plant growth mediums have concentrated on select features withoutproviding a truely balanced medium which approaches the idea asdiscussed above. U.S. Pat. No. 3,441,400 uses an angular porous mineralcarrier in a plant growth media. This material serves as a soil adjuvantand as a nitrogen containing ingredient which resists leaching. U.S.Pat. No. 3,831,317 uses a polymeric pulp material as a plant growthmedium. This material is said to have enhanced capillary action whichaids in the plants water and fertilizer requirements. U.S. Pat. No.4,241,537 uses an aqueous polyurethane gel as a plant growth medium.This material is described as useful for supplying water to the plants.None of the compositions described in the above cited patents addressall the factors which make a soil composition ideal.

Other examples include U.S. Pat. Nos. 3,524,279; 4,168,962 and4,196,543. All of these provide growing mediums which are rigid orshaped self-supporting structures. As such, all of these lack some ofthe features found in the ideal multipurpose media.

Accordingly, there remains a need in the art for a plant growth mediawhich provides a low cost composition which optimizes the features ofthe ideal plant growth media.

SUMMARY OF THE INVENTION

The present invention relates to a platn growth media suitable forgerminating seeds, growing plants and other related uses that plantgrowth media are typically used in the field of horticulture.

The invention comprises a blend of ingredients whichprovides acombination of properties for an ideal plant growing environment. Thegrowth media comprises a blend of mineral wood, a cationic exchangematerial such as vermiculite and perlite, and an acidic phenolic resin.

The product is conveniently formulated by combining the vermiculiteand/or perlite, mineral wood and powdered phenolic foam resin,subjecting the combination to a mixing step to mix the ingredients andpartially break up the mineral wood into limps of about 1" in diameter;and then placing the mixture into a hammer mill to produce a blend. Thefinal blend appears to the naked eye as tufts of cotton (actuallymineral wood) about 1/8" to 1/2" in diameter with phenolic resin powderand specs of vermiculite dispersed throughout the mixture. The tufts ofmineral wool take on a grey-green color due to the fine particles ofphenolic resins dispersed in and on the network of mineral wool fibers.

Each of these ingredients plays an important role in providing a plantgrowth medium having a broad spectrum of ideal features. Furthermore,the combination of ingredients provides additional water adsorbency notfound in any of the individual ingredients. Additionally, the form andstructure of the final product, being composed of tufts of brokenmineral wool fibers with phenolic foam powder and vermiculite dispersedtherein, makes the mixture flowable, lightweight, highly adsorbentwithout sacrificing the qualities of cohesiveness and the ability toanchor the roots. The composition also has an enhanced ability to holdand release nutrients to the growing plant. furthermore, the compositionis sufficiently cohesive in the wet state so that it can be periodicallywashed or leached with water to remove unwanted accumulation ofcontaminants such as salts, without the media itself being washed away.

The phenolic resin is particularly useful because it provides for aparticular pH level over a long period of time without the necessity ofadding conventional pH adjuvants such as lime or sulfur. The powderedphenolic resin provides a stable pH level while also providing enhancedadsorbency of the water when combined with the other ingredients. Thephenolic resin is used in the form of particulates, preferably in theform of a powder. Most preferably the powder is made by pulverizing amass of phenol-formaldehyde foamed resin.

The fine particles of phenolic resin have adsorption qualities withoutthe addition of detergent or surfactant compositions. In addition, thepowdered phenolic foam resin adheres to the tufts of mineral wool andvermiculite. Thus, the powdered foam resin provides for certainadvantages such as longer pH regulation than that obtainable by simplyadding conventional pH adjuvants such as lime or sulfur to thecomposition.

The mineral wool in the form of tufts of broken fibers allows thematerial to be flowable while providing for sufficient cohesivenesswhich prevents the composition from being easily spilled from itscontainer. This property is particularly important when the product isused in certain types of planters which have vertical walls containing aplurality of openigns for plants, such as strawberry pots. The tufts ofmineral wool also provide the uniform dispersal of the fine phenolicfoam powder particles. The dispersal property is augmented by thesurface adhesion which causes the powder to adhere to the multitude offibers in each tuft. This adhesion prevents the segregation and loss ofthe fine powder. Also, the expanded vermiculite particles tend to clingto themineral wood tufts so that the tendency of segregation fordifferent types and density of particles is minimized. This particularstructure results in the ability to adsorb greater quantities of waterwithout sacrificing the optimization of other factors. Additionally, themineral wool, being essentially inert in the mixture, is not subject todecay and thus it will provide uniform results over an extended periodof time.

The expanded vermiculite is useful because of its water adsorptionqualities, cationic exchange capacilities and ability to hold nutrients.

The materials used to make the composition of this invention are free ofcontamination of toxic agents and are substantially sterile with respectto germs such as plant pathogens. The composition also contains asufficient amount of air to supply the oxygen requirements for rootsgrowing in the media. Furthermore, this air is retained even afteroverwatering so long as means is provided for excess water to drainfromthe composition. Also, the materials used in this composition arenon-reactive with fertilizer materials. For example, nitrogens will notbe used up as it might be in a composition which contains various typesof decomposable organic mateials such as sawdust and peat.

All of the above ingredients are low in cost and readily available andlightweight for easy shipping, thus making them particularly suitablyfor formulation into this new composition.

It is an object of this invention to provide a composition useful inprocesses of growing plants.

It is also an object of this invention to provide a low cost pH adjustedplant growth media which optimizes the ideal features of a platn growthmedia without compromising or sacrificing any of the ideal features.

It is also an object of this invenion to provide a low cost,lightweight, pH adjusted plant growth media which is highly adsorbentwhile retaining the ability to anchor the plant roots; and is flowablefor easy handling yet is sufficiently cohesive to prevent unwantedspilling from plant containers.

It is also an object to provide a plant growth media having the abovementioned properties and which is also non-toxic and free of diseasecausing agents.

It is also an object to provide a method of making a plant growth mediahaving the above mentioned properties.

It is also an object to provide a method of growing plants in the abovedescribed plant growth media.

These objects and other objects will become apparent to those skilled inthe art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The composition contains vermiculite, powdered phenolic foam resin andmineral wool. The ingredients and their form and structure contribute tothe unique properties of this invention.

In the preferred embodiment, the composition contains ninety parts ofmineral wool; thirty-eight parts of foamed phenolic resin and twenty-twoparts of vermiculite. All parts given in this specification are parts byweight unless indicated otherwise. The amounts of each ingredient canvary to suit particular plants, especially the needs of particularplants being used with the composition. In general, the major ingredientis the mineral wool which provides the built of the final product.Lesser quantities, each of the resin and vermiculite, can be blendedwith the mineral wool. For most plant growing needs, the formulationwill vary from the above mentioned preferred embodiment by plus or minustwenty percent (20%) for each ingredient.

the structure of the ingredients in the final product of the preferredembodiment is also important. The mineral wood is in the form of tufts.The tufts are formed by taking conventional mineral wool and subjectingit to forces which pull apart and break the mineral fibers into shortlength fibers and mixing the broken fibers to form tufts. The fibers arepulled apart and broken up into lengths which are long enough so thatthey are capable of forming the tufts.

In a preferred embodiment, the fibers are subjected to breaking andmixing forces to break and mix the fibers to such an extent that tuftsare formed which are about 1/8" to 1/2" in diameter. Larger or smallertufts can be used but this size range is found to be particularlyconvenient for most planting purposes.

The breaking and mixing action canb e carried out in any conventionaldevice known to those skilled in the art for this purpose. It is alsopossible to pull apart and break the fibers by hand to form the tufts.In a preferred embodiment, the mineral wool is first placed in a mixingapparatus for mixing and breaking the fibers. The mineral wool is mixeduntil tufts of about 1" in diameter are formed. Thereafter, the 1" tuftsare placed in a hammer mill for further processing until tufts of about1/8" to 1/2" in diameter are formed.

Conventional mineral wool or rock wool is used in the invention. Mineralwool, sometimes referred to as rock wool, is a common ingredient used inmany fields of technology such as the field of insulation. It is a finefibrous "wool like" material made by forming fine filaments of mineralfiber from a molten rock. Many processes are known for making themineral wool. Examples of this type of product are disclosed in U.S.Pat. Nos. 2,193,982; 2,051,279 and 2,155,107, the specifications ofwhich are incorporated herein by reference.

Preferably the mineral wool for the present invention is made from asilica containing mineral such as basalt. Other types of mineral arepermissible so long as they do not contain harmful ingredients. Evenfiberglass of the type used in typical home insulation is acceptable butis not preferred because it is less adsorbent and is somewhat irritableto personnel who handle it. For the purposes of this invention, the term"mineral wool" includes glass wool and the like.

The vermiculite is conventional vermiculite as is currently used in soilconditioners and other types of plant growth formulation. Preferably,expanded or exfoliated vermiculite is used. Vermiculite is a micaceousmineral, chemically identified as a hydrated magnesium-aluminum-ironsilicate, with a platelet-like structure which exfoliates or expandswhen heated or subjected to certain chemical processes. The mineraloccurs naturally in an unexpanded state and is mined in conventionalmanners. The mined ore is milled to controlled sizes and thenexfoliated. The exfoliation is generally accomplished by dropping themilled ore in a continuous stream through a furnace, the chambertemperature of which has variously been reported in ranges of from about1400° to 2200° F., depending upon the design of the furnace and theburners, and on the location and type of temperature measuring means.During exfoliation, each granule or particle of vermiculite expands toseveral times its original size and traps within itself thousands of aircells.

Any suitable method may be used to expand or exfoliate the vermiculite.Many methods are known for producing suitable expanded vermiculite.Exemplitive methods and products are disclosed in U.S. Pat. Nos.2,791,496; 3,062,753; 2,945,820 and 3,459,531, the specifications ofwhich are incorporated herein by reference.

The expanded vermiculite is broken up into small size pieces. In thepreferred embodiment, the largest particles of vermiculite are about thesize of the smaller tufts, or about 1/8" diameter although most of themare considerably smaller so that they give the appearance of specks ofvermiculite in and on the tufts. A conventional hammer mill may be usedto break up the vermiculite.

The phenolic resin is a phenol-formaldehyde resin. Preferably it is afoamed resin in the form of a block or mass which is then pulverizedinto a powder. The resin may be foamed by any conventional method. Thepowder is made sufficiently fine so that it adheres to the mineral wooltufts within the interstices thereof and does not become segretated fromthe tufts during ordinary handling.

Phenol-formaldehyde foam resins are welll known to those skilled in theart. Typical examples are described in U.S. Pat. Nos. 2,278,741 and4,166,162, the specifications of which are incorporated herein byreference. In the preferred embodiment, the phenol-formaldehyde resin isformulated so that it has an acidic pH. A particularly useful resinforthis embodiment is the phenol-formaldehyde describe in U.S. Pat. No.2,753,277, the specification of which is incorporated herein byreference.

In a preferred embodiment of this invention, the foamedphenol-formaldehyde resin described in U.S. Pat. No. 2,753,277, ispulverized into a powder and mixed in with the vermiculite and mineralwool as defined above. It is not necessary, however, for theincorporation ofany wetting aent or surfactant into thephenol-formaldehyde because the structure of the final compositiondoesnot require a wetting agent to achieve its unusually high wateradsorption.

In a preferred embodiment, the final product is obtained by mixing themineral wool with #3 size expanded vermiculite and acidicphenol-formaldehyde foam which has been previously pulverized to apowder. The ingredients are mixed until the mineral wool breaks up andforms tufts of about 1" in diameter. At that point, the entiremixture issubjected to the action of a hammer mill unitl tufts are generallyreduced in size to about 1/8" to about 1/2" in diameter, it beingrealized tha the hammer mill process will result in a distribution ofsizes withsome tufts being smaller than 1/8" in diameter and some whichmay be slightly larger.

The mixing and milling also reduces the diameter of the vermiculite to asize which ranges generally from powder size particles to pieces whichare about the size of the 1/8" tufts. The size range of the vermiculitein the final product gives the appearance of "specks" of vermiculite inand one the tufts of mineral wool.

The material of the above described preferred embodiment is flowable andis capable of adsorbing large quantities of water. It is also capable ofproviding superior anchorage for the plant roots due to the nature ofthe tufts. The property of root anchorage is provided withoutsacrificing the properties of flowability of water adsorption. Thepresence of the powdered acidic phenolic resin in the interstices of thetufts provides a long lasting means of assuring properpH for acid lovingplants such as strawberries. Furthemore, since the resin adhers to themineral fiber, it does not become segregated therefrom nor is it easilywashed from the composition.

Although the composition is flowable, it is sufficiently cohesive sothat it is not easily lost through the holes in the planters. Also, itholds fertilizer due to the ionic effects oif the vermiculite, yet itcan be leached from time to time to wash away accumulated contaminantswithout fear of losing the particulate materials which make up thecomposition.

The composition is suitable for a wide variety of horticultural uses. Assuch, any of the usual adjuvants may be added to the comosition toaccomplish their intended purposes. For eample, fertilizer, both liquidand solid, are desirably used with the composition. Biocidalcompositions for efficient disease or insect control may also be added.

The composition of this invention is particularly suitable for acidloving plants such as strawberries. Strawberries are often grown inspecial receptacles such as pots which have a plurality of side holes.Typically, a strawberry plant grows out of each of these holes. However,due to the positions of the holes, it is very easy for the soil or othergrowing medium to spill out of the holes, especially immediately afterplanting since the roots have not fully developed to a point where theycan hold in the soil. The unique cohesiveness of the growing medium ofthis invention prevents the soil from spilling out of the holes yet itis sufficiently flowable so that no difficulty is encountered whenfilling the pot with the medium.

The composition is also useful for germinating seeds. Seeds can beplanted in this material and treated with any suitable adjuvant whichaids in seed germination. Thereafter, the developing plant can be grownin accordance with accepted methods of horticulture.

Although it is preferable to formulate the mixture containing mineralwool, acidic phenolic resin and a cation exchange material such asvermiculite and perlite, suitable compositions may be made evenif theresin or cation exchange material were omitted. Thus, a compositioncontaining tufts of mineral wool in combination with the vermiculite orperlite may be made. Such a compositionwould be preferred if an acidartifical soil were not desired,f or example, as when one wishes to growplants which require a neutral or somewhat alkaline soil. Also, thevermiculite or perlite could be omitted from the composition to resultin an artifical soil composed of tufts of mineral wool with particles ofphenol-formaldehyde dispersed throughout the interstices thereof.

The following example is given as a preferred embodiment of theinention.

Thirty-eight (38) pounds of acidic phenol-formaldehyde foam resin waspulverized to a powder. The foam is identified as "Oasis" which is aacidic phenol-formaldehyde foam resin sold by Smithers Company of Kent,Ohio. The powdered phenolic resin was mixed with inety (90) pounds ofmineral wool and twenty-two (22) pounds of #3 expanded vermiculite. Thevermiculite was obtained from W. R. Grace and Company and the mineralwool was purchased from U.S. Mineral Wool Company in New Jersey. Thecompositionwas mixed until the mineral wool was broken up sufficientlyto form tufts of about 1" in diameter. At that point, the material wastransferred to a hammer mill for further processing until tufts of about1/8" to 1/2" diameter were formed. The final product was gray-green incolor and had the appearance of tufts of cotton with specks ofvermiculite dispersed therein.

While the present invention has been described in terms of certainpreferred embodiments and exemplified with respect thereto, one skilledin the art will readily appreciate that various modification, changes,omissions and substitutions may be made without departing from thespirit thereof. It is intended, therefore, that the present invention belimited solely by the scope of the following claims.

I claim:
 1. The method of making a plant growth media which comprisesmixing mineral wool fiber with expanded vermiculite particles andpowdered phenol-formaldehyde resin having an acid pH, said mixing beingcontinued until the mineral wool forms tufts of about 1" in diameter andthereafter subjecting the mixture to a hammer mill until the tufts arereduced in size to about 1/8"-1/2" in diameter.
 2. The method of claim12 wherein the mineral wool is present in an amount of 72-108 parts byweight; the phenol-formaldehyde is present in an amount of 30-47 partsby weight and the vermiculite is present in an amount of 18-26 parts byweight.